Ben Bowen asked this question on Google+:
Seen this debated elsewhere: Is there any benefit to varying your company "description" across listings? Or can you just cut and paste your Yelp (or whatever) description?
If there is a benefit, it would be quite small. Although there is no exact understanding of how Google uses directory descriptions, it would seem to be a minor or non-issue. I have seen no indication that strong directory entries like Yellow Pages, Superpages or Yelp are not shown in search results due to a duplicate description.
As a proof of the low esteem in which Google holds descriptions, look at how little the Google+ description field is actually used by Google itself. The descriptions entered by the business owner only appear on a page that is hardly seen at all by users. Since reviews have been pushed to the front page and Places search was removed, a user needs to click between two and four times to get to the Google+ "About" page where the description resides and that just isn't going to happen.
At recent LocalU events, Googler Joel Headley noted that these business descriptions are not used in ranking and should be thought of as a business's elevator speech. That may have been different in the past, but I think Google now sees owner-written descriptions as pretty much worthless -- i.e., prone to spam and not of value to searchers. If they were perceived as valuable, Google would show them in the knowledge panel on a branded or category search.
With the new dashboard you can see Google moving totally away from free-form business inputs in areas like categories, enhanced details and -- as mentioned above -- by minimizing who sees the description.
On the other hand, I think categories on certain highly trusted third party directories are carefully examined and used by Google to expand their categorical understanding of what a business does. Given the removal of custom categories going forward this will become of increasing importance.